To understand evolution, we need to understand the age of the Earth.
So how old is the Earth? And how do we know?
Earth Science: Crash Course History of Science #20
How Do We Know How Old the Earth Is?
How We Know The Earth Is Ancient
World's Most Asked Questions: How Old is Earth?
Four ways to understand the Earth's age
"Creation's Story - Evidence for an Ancient Earth"
Is radiometric (or radioisotope) dating reliable? Yes. Radiometric Dating Does Work!